Rollers

[nijwnfi]

On a Century CETME, my bolt gap is .005in, bolt is unground, measures 1.835". To improve bolt gap should +4 rollers do the trick? Should I replace the locking piece, and if so, where can I find one? I checked my rollers, they are unmarked, measure 8.00mm. Would +4 rollers theoretically equal .009 bolt gap? Just learning here, appreciate any help.

[M1 Tanker]

+4 rollers will give you a gap of .014, which is perfect. A new locking piece will give you about another .002 to .003. Jorge in Spain has locking pieces still I believe.

[nijwnfi]

Thanks for the info, great work on the site too.

[Rampager]

If you need +4's RTG is a great place to get them BTW, that's where I got mine.

[okie shooter]

You might want to check you rollers before you get too far into it, if they are oversized already you wont gain much from new ones so checking what you have would be a good idea.

[drine]

Please buy all to include a locking piece. I say this because I had a bolt gap of .004. Adding +4 rollers only gave me up to .007. I bought a new bolt head and locking piece because I wanted new parts and a better gap. Adding my new head, LP, and +4 rollers yielded a .014 gap.
My rifle still wouldn't group so now I have the barrel pulled.

To me, plus size rollers will get you by probably for your life time..... New parts are getting scarce so I'd get them just to have.

That's just me, you may want to spend your dough elsewhere.

[tomoshenko]

My .000 gap went to .006 with +4s, new bolthead & LP.

[hunter_la5]

Adding +4 rollers only gave me up to .007.


really? did you have oversized rollers to begin with? mine went from .007 to .016ish

[M1 Tanker]

If ya'll didn't get .009+ out of +4 rollers, then you some larger rollers to begin with.

[drine]

I truely got the measurements I stated. I mic'd the rollers in already and 8.0 was what I got. It's a good mic and I'm not a newbie to machining type work.
That is why I bought new parts and now the rebarrel. I don't know why I got the measurements I did but here's the klinker..My cocking tube is cracked at the forward end of the notch and I'm sure I never correctly measured the clearance between the bolt carrier end and the cocking tube support/handle assembly. I will play close attention to that. I will rebarrel and set the boltgap without the cocking handle or support in then see what I get when complete. Hopefully I won't have to fix it but will.
This thread is the exact reason I like this site so much. A newbie should hear boltgap first and most times that's good enough. There's too much more that can be wrong and even more that CAI could've messed up. The technical expertise and experience of these members here get past the simple fix.
I don't know for sure why I got what I got but I did and just wanted to throw all possibilities on the table.

[drine]

While tinkering around without the barrel out I wanted to check to see what the boltgap might be if any at all. With the worn parts I can actually get a .004 in. Since the barrel isn't in and forcing anything back maybe there is some play. Anyhow, my barrel looked about flush with the trunnion before I pressed it out. Is it possible I had a zero boltgap to start?
I asked a question a long way back as to where the rollers contact the trunnion and if it changes with gap? Or should the rollers bottom out in the same place every time.
If I'm not making anyone else sick, I'm getting there myself. I'm just ready to get it fixed and blast the heck out of the range. It would be alright if I were building a parts kit but I'm repairing a CAI Blackwidow. BTW I called them a month or two ago and they are real "A" holes.

[M1 Tanker]

Here is the relationship. If you press the barrel in deeper you have more meat on the trunnion as to where the rollers come to rest.

245

[drine]

I have a new triple frame to put on when I get the barrel finished. Will the barrel also need slotting for the sling eyelet pin?

[Seattlefungus]

Yes, That's the why of Perro saying not to use the old barrel hole. Turn the whole barrel 180 and drill new hole for barrel pin & triple frame notch... (From the onle forum..)

[nijwnfi]

Well I'm definitely ordering a Locking Plate from Jorge. I can feel the wear on the machined flats. Once gap is increased, next comes a scope.